Advanced Functional Materials

Cover image for Vol. 21 Issue 20

October 21, 2011

Volume 21, Issue 20

Pages 3797–3997

  1. Cover Picture

    1. Top of page
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    3. Inside Front Cover
    4. Back Cover
    5. Contents
    6. Feature Article
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    8. Full Papers
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    1. Carbon Nanotubes: Super-Fast Switching of Twisted Nematic Liquid Crystals on 2D Single Wall Carbon Nanotube Networks (Adv. Funct. Mater. 20/2011) (page 3797)

      Won-Kyu Lee, Yeon Sik Choi, Young-Gu Kang, Jinwoo Sung, Dae-Shik Seo and Cheolmin Park

      Version of Record online: 18 OCT 2011 | DOI: 10.1002/adfm.201190088

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      A high-performance liquid crystal (LC) alignment layer of ultrathin single-walled carbon nanotubes (SWNTs) is developed along with a conjugated block copolymer nanocomposite that is solution-processible for con-ventional twisted nematic (TN) LC cells. On page 3843, Dae-Shik Seo, Cheolmin Park, and co-workers show that a LC cell prepared on this extremely trans-parent nanocomposite gave rise to superfast switching of the TN LC molecules, four times faster than that on a commercial polyimide layer.

  2. Inside Front Cover

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Contents
    6. Feature Article
    7. Frontispiece
    8. Full Papers
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    1. Graphene vs Carbon Nanotubes in Electronic Devices: Graphene Versus Carbon Nanotubes in Electronic Devices (Adv. Funct. Mater. 20/2011) (page 3798)

      Chandan Biswas and Young Hee Lee

      Version of Record online: 18 OCT 2011 | DOI: 10.1002/adfm.201190089

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      Graphene and CNT exhibit excellent electronic and optoelectronic properties. In a Feature Article on page 3806, Young Hee Lee and Chandan Biswas review recent progress in carbon nanotube and graphene research. The review compares the electronic and opto-electronic properties of carbon nanotubes and graphene, and their performances in devices such as transparent conducting films (transparency and sheet resistance) and field-effect transistors (device types, ambipolarity, mobility, doping strategy, FET-performance, logic and memory operations).

  3. Back Cover

    1. Top of page
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    3. Inside Front Cover
    4. Back Cover
    5. Contents
    6. Feature Article
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    8. Full Papers
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    1. Molecular Engineering: Engineering Molecular Organization of Naphthalenediimides: Large Nanosheets with Metallic Conductivity and Attoliter Containers (Adv. Funct. Mater. 20/2011) (page 3998)

      M. B. Avinash and T. Govindaraju

      Version of Record online: 18 OCT 2011 | DOI: 10.1002/adfm.201190090

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      On page 3875, M. B. Avinash and T. Govindaraju report the molecularly engineered self-assembly of phenylalanine methylester-appended naphtha-lenediimide, an organic n-type semiconductor, into large free-floating nanosheets and attoliter containers. Nanosheets with high-level molecular ordering exhibit metallic conductivity in the undoped state. Chlorinated co-solvents promote molecular organization into attoliter volume con-tainers, such as nanocups, mesocups, and bowl-like novel and complex architectures, through halogen bonding.

  4. Contents

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Contents
    6. Feature Article
    7. Frontispiece
    8. Full Papers
    9. Frontispiece
    10. Full Papers
  5. Feature Article

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Contents
    6. Feature Article
    7. Frontispiece
    8. Full Papers
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    10. Full Papers
    1. Graphene Versus Carbon Nanotubes in Electronic Devices (pages 3806–3826)

      Chandan Biswas and Young Hee Lee

      Version of Record online: 14 SEP 2011 | DOI: 10.1002/adfm.201101241

      Thumbnail image of graphical abstract

      Graphene and CNT exhibit excellent electronic and optoelectronic properties. This Feature Article reviews the recent progresses of carbon nanotubes and graphene research and compares their electronic and optoelectronic properties and device performances, such as transparent conducting films (transparency and sheet resistance) and field-effect transistors (FETs) (device types, ambipolarity, mobility, doping strategy, FET-performance, logic and memory operations), in detail.

  6. Frontispiece

    1. Top of page
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    3. Inside Front Cover
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    5. Contents
    6. Feature Article
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    1. Light-Emitting Diodes: Two Distinct Origins of Highly Localized Luminescent Centers within InGaN/GaN Quantum-Well Light-Emitting Diodes (Adv. Funct. Mater. 20/2011) (page 3827)

      Suman De, Arunasish Layek, Archana Raja, Abdul Kadir, Mahesh R. Gokhale, Arnab Bhattacharya, Subhabrata Dhar and Arindam Chowdhury

      Version of Record online: 18 OCT 2011 | DOI: 10.1002/adfm.201190086

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      The true-color photoluminescence microscopy image of an InGaN alloy- based quantum-well LED shows the presence of highly localized emission centers which originate from modulation of the quantum-well potential landscape along lateral dimensions. On page 3828, Arindam Chowdhury and co-workers show that the carrier localization in efficient radiative traps with diverse transition energies results from both local indium compositional fluctuations (orange-red dots) as well as interface-morphology related inhomogeneities (green dots).

  7. Full Papers

    1. Top of page
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    3. Inside Front Cover
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    5. Contents
    6. Feature Article
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    1. Two Distinct Origins of Highly Localized Luminescent Centers within InGaN/GaN Quantum-Well Light-Emitting Diodes (pages 3828–3835)

      Suman De, Arunasish Layek, Archana Raja, Abdul Kadir, Mahesh R. Gokhale, Arnab Bhattacharya, Subhabrata Dhar and Arindam Chowdhury

      Version of Record online: 11 AUG 2011 | DOI: 10.1002/adfm.201100894

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      Spectrally-resolved photoluminescence imaging has been performed on thousands of individual localized luminescent centers within green emitting In0.22Ga0.78N quantum-well LEDs by selectively generating carriers within the alloy layers. These measurements reveal the presence of two distinct types of radiative centers with stark differences in their optoelectronic properties, suggesting that both nanometer-scale variations of the indium content within the alloy and thickness fluctuations of active layer can coexist within the same quantum-well sample.

    2. Ultrafast Direct Ablative Patterning of HOPG by Single Laser Pulses to Produce Graphene Ribbons (pages 3836–3842)

      Narendra Kurra, Abhay A. Sagade and Giridhar U. Kulkarni

      Version of Record online: 31 AUG 2011 | DOI: 10.1002/adfm.201100832

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      Ultrafast, large-area and direct patterning of HOPG (highly oriented pyrolytic graphite) is achieved through single laser pulse ablation in presence of a phase mask. The modulating laser intensity can ablate the carbon material periodically to produce different types of patterns on HOPG. AFM topography of those patterns reveals that no modification of the regions adjacent to the periodic ablated patterns. Thus patterned surfaces of HOPG are used as source for graphitic and graphene ribbons enabled by PDMS stamp based transfer. The transferred multi and few layer graphene ribbons are of high quality.

    3. Super-Fast Switching of Twisted Nematic Liquid Crystals on 2D Single Wall Carbon Nanotube Networks (pages 3843–3850)

      Won-Kyu Lee, Yeon Sik Choi, Young-Gu Kang, Jinwoo Sung, Dae-Shik Seo and Cheolmin Park

      Version of Record online: 24 AUG 2011 | DOI: 10.1002/adfm.201101345

      Thumbnail image of graphical abstract

      A high performance liquid crystal (LC) alignment layer of ultra-thin single wall carbon nanotubes (SWNTs) is developed along with a conjugated block copolymer nanocomposite that is solution-processible for conventional twisted nematic (TN) LC cells. A LC cell prepared on this extremely transparent nanocomposite gave rise to superfast switching of the TN LC molecules, four times faster than that on a commercial polyimide layer.

    4. Robust and Highly Efficient Free-Standing Carbonaceous Nanofiber Membranes for Water Purification (pages 3851–3858)

      Hai-Wei Liang, Xiang Cao, Wen-Jun Zhang, Hong-Tao Lin, Fei Zhou, Li-Feng Chen and Shu-Hong Yu

      Version of Record online: 15 AUG 2011 | DOI: 10.1002/adfm.201100983

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      Free-standing carbonaceous nanofiber (CNF) membranes are used to remove dye pollutants from water in a highly efficient way that combines the excellent adsorption behavior of CNFs (high adsorption rate and capacity) and the functionality of nanofibrous membranes (filtration adsorption with high flux).

    5. Electrochemical Na Insertion and Solid Electrolyte Interphase for Hard-Carbon Electrodes and Application to Na-Ion Batteries (pages 3859–3867)

      Shinichi Komaba, Wataru Murata, Toru Ishikawa, Naoaki Yabuuchi, Tomoaki Ozeki, Tetsuri Nakayama, Atsushi Ogata, Kazuma Gotoh and Kazuya Fujiwara

      Version of Record online: 11 AUG 2011 | DOI: 10.1002/adfm.201100854

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      Based upon high capacity and reversibility Na insertion of hard-carbon and layered NaxNi0.5Mn0.5O2 electrodes, the novel Na-ion battery of hard-carbon/NaNi0.5Mn0.5O2 is fabricated and electrochemically tested in organic electrolyte solutions. The 3-volt Na-ion battery with environmentally and cost friendly materials demonstrates steady cycling performance and is expected to be an alternative to secondary Li-ion batteries.

    6. Triangular Graphene Grain Growth on Cube-Textured Cu Substrates (pages 3868–3874)

      Jianwei Liu, Judy Wu, Christina M. Edwards, Cindy L. Berrie, David Moore, Zhijun Chen, Victor A. Maroni, M. Parans Paranthaman and Amit Goyal

      Version of Record online: 13 SEP 2011 | DOI: 10.1002/adfm.201101305

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      The growth of graphene has been carried out on cube-textured (100) oriented Cu (CTO-Cu) foils using chemical vapor deposition (CVD). Well-aligned triangles self-assembled on CTO-Cu during CVD. The nucleation of triangular graphene grains on CTO-Cu has been demonstrated. The triangles on the CTO-Cu are predominantly in the shape of right triangles. In some cases, equilateral triangles are also observed. (Figure 2a and 2b)

    7. Engineering Molecular Organization of Naphthalenediimides: Large Nanosheets with Metallic Conductivity and Attoliter Containers (pages 3875–3882)

      M. B. Avinash and T. Govindaraju

      Version of Record online: 13 JUL 2011 | DOI: 10.1002/adfm.201101001

      Thumbnail image of graphical abstract

      The molecularly engineered organization of phenylalanine methylester-appended naphthalenediimide, an organic n-type semiconductor, into large free-floating nanosheets and attoliter containers is reported. Nanosheets with high-level molecular ordering enabled metallic conductivity in the undoped state. Chlorinated co-solvents promote the molecular organization into attoliter volume containers, such as nanocups, mesocups, and bowl-like novel and complex architectures, through halogen bonding.

    8. Deformation Strengthening of Biopolymer in Nacre (pages 3883–3888)

      Zhi-Hui Xu and Xiaodong Li

      Version of Record online: 3 AUG 2011 | DOI: 10.1002/adfm.201100167

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      Directly testing nacre biopolymer strands using atomic force microscopy reveals that nacre biopolymer can strengthen itself during deformation, a phenomenon that can be explained by a coiled spring model. The findings advance the understanding of nacre's toughening mechanisms, provide additional design guidelines for developing biomimetic nanomaterials, and lay a constitutive foundation for modeling the deformation behavior of nacre.

    9. New Solution-Processable Electron Transport Materials for Highly Efficient Blue Phosphorescent OLEDs (pages 3889–3899)

      Eilaf Ahmed, Taeshik Earmme and Samson A. Jenekhe

      Version of Record online: 30 AUG 2011 | DOI: 10.1002/adfm.201100848

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      Multilayered high-performance blue PhOLEDs are fabricated by orthogonal solution-processing enabled by new dendritic oligoquinoline electron-transport materials. The resulting blue PhOLEDs have a luminous efficiency of 30.5 cd A−1 at a brightness of 4130 cd m−2 with an external quantum efficiency of 16.0%. The high electron mobility (3.3 × 10−3 cm2 V−1 s−1) and vertically oriented nanopillars of solution-deposited ETLs partly explain the excellent performance.

    10. Simultaneous Electrical and Thermoelectric Parameter Retrieval via Two Terminal Current–Voltage Measurements on Individual ZnO Nanowires (pages 3900–3906)

      Yang Liu, Zhiyong Zhang, Xianlong Wei, Quan Li and Lian-Mao Peng

      Version of Record online: 24 AUG 2011 | DOI: 10.1002/adfm.201100701

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      The extraction of electrical and thermoelectric parameters simultaneously from individual semiconducting nanowires via two terminal current–voltage measurements is demonstrated, using ZnO NWs as an example. The thermal conductivity of ZnO NWs is found to decrease faster than the equation image trend expected by the Umklapp model, but obeys the equation image relation, which results from four-phonon processes at high temperatures.

    11. New Ultraviolet Photodetector Based on Individual Nb2O5 Nanobelts (pages 3907–3915)

      Xiaosheng Fang, Linfeng Hu, Kaifu Huo, Biao Gao, Lijuan Zhao, Meiyong Liao, Paul K. Chu, Yoshio Bando and Dmitri Golberg

      Version of Record online: 8 SEP 2011 | DOI: 10.1002/adfm.201100743

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      A new and high-performance ultraviolet photodetector was successfully constructed from an individual Nb2O5 nanobelt for the first time. The as-constructed photodetector exhibited a high photosensitivity, light selectivity, excellent photocurrent stability, and high external quantum efficiency (6070%), demonstrating that Nb2O5 nanobelts is a perfect candidate for visible-blind ultraviolet-light sensors, especially for working in the UV-A band.

    12. Length-Scale Mediated Differential Adhesion of Mammalian Cells and Microbes (pages 3916–3923)

      Yi Wang, Guruprakash Subbiahdoss, Jan Swartjes, Henny C. van der Mei, Henk J. Busscher and Matthew Libera

      Version of Record online: 30 AUG 2011 | DOI: 10.1002/adfm.201100659

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      To create biomaterials surfaces that promote mammalian cell adhesion while inhibiting microbial colonization, cell-adhesive surfaces are patterned with submicrometer-sized, non-adhesive microgels. The inter-gel spacing is varied and it is found that, at inter-gel spacings comparable to microbial dimensions (∼1–2 μm), the rate of microbial adhesion significantly drops while the adhesion and spreading of osteoblast-like cells is preserved. Such length-scale-mediated differential cell adhesion is a new antibiotic-free mechanism with which to promote healing while reducing the probability of biomaterials-associated infection.

    13. Generation of Amphiphilic Janus Bubbles and Their Behavior at an Air–Water Interface (pages 3924–3931)

      Teresa Brugarolas, Bum Jun Park, Myung Han Lee and Daeyeon Lee

      Version of Record online: 9 SEP 2011 | DOI: 10.1002/adfm.201100954

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      Amphiphilic Janus bubbles are generated by selectively depositing gold onto the top hemisphere of dried nanoparticle-shelled bubbles and, subsequently rendering the gold surface hydrophobic. Amphiphilic Janus bubbles at an air–water interface interact with each other via long-ranged capillary attraction, which is induced by the random undulation of three phase contact line around the boundary between polar and apolar hemispheres.

  8. Frontispiece

    1. Top of page
    2. Cover Picture
    3. Inside Front Cover
    4. Back Cover
    5. Contents
    6. Feature Article
    7. Frontispiece
    8. Full Papers
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    10. Full Papers
    1. Carbon Nanotubes: Current-Induced Restructuring and Chemical Modification of N-Doped Multi-walled Carbon Nanotubes (Adv. Funct. Mater. 20/2011) (page 3932)

      Zabeada Aslam, Rebecca Nicholls, Antal Koós, Valeria Nicolosi and Nicole Grobert

      Version of Record online: 18 OCT 2011 | DOI: 10.1002/adfm.201190087

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      On page 3933, Zabeada Aslam, Nicole Grobert, and co-workers show that the electrical properties of multi-walled carbon nanotubes (MWCNTs) can be manipulated by introducing dopants. The image shows the current-induced restructuring of a N-doped MWCNT, as a result of Joule heating. This leads to the removal of the dopant and a significant change in its electronic behaviour and has serious implications for the use of doped-CNTs as electronic components.

  9. Full Papers

    1. Top of page
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    5. Contents
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    1. Current-Induced Restructuring and Chemical Modification of N-Doped Multi-walled Carbon Nanotubes (pages 3933–3937)

      Zabeada Aslam, Rebecca Nicholls, Antal Koós, Valeria Nicolosi and Nicole Grobert

      Version of Record online: 17 AUG 2011 | DOI: 10.1002/adfm.201101036

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      For N-doped multi-walled carbon nanotubes (CNTs) to be fully exploited as electrical components in the miniaturized electronics industry, their behavior in the presence of an applied current must be fully understood. Current-induced restructuring of CNTs has a dominant effect on the dopant which in turn influences their electronic properties.

    2. In Situ Observation of Strain Development and Porosity Evolution in Nanoporous Gold Foils (pages 3938–3946)

      Christian J. Dotzler, Bridget Ingham, Benoit N. Illy, Kia Wallwork, Mary P. Ryan and Michael F. Toney

      Version of Record online: 12 SEP 2011 | DOI: 10.1002/adfm.201100735

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      The formation and coarsening of nanoporous gold by dealloying is studied with in situ X-ray diffraction and small angle X-ray scattering. Distinct characteristic dealloying stages are observed. The initial formation of pores and mounds results in an increase of the average strain due to capillary forces. After dissolution, strain is reduced due to self-similar coarsening of a bicontinuous morphology.

    3. Magnetic Molecularly Imprinted Polymer Nanocomposites via Surface-Initiated RAFT Polymerization (pages 3947–3953)

      Carlo Gonzato, Matthieu Courty, Pamela Pasetto and Karsten Haupt

      Version of Record online: 17 AUG 2011 | DOI: 10.1002/adfm.201100466

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      Surface-initiated RAFT polymerization with a trithiocarbonate agent allows for the controlled synthesis of nanocomposite particles containing a superparamagnetic iron oxide core for magnetic susceptibility and a molecularly imprinted polymer layer for specific molecular recognition. The 40-nm composite particles with a 7-nm MIP shell can be further functionalized by taking advantage of the living nature of the active RAFT fragments to fine-tune their surface properties.

    4. Efficient Synthesis of Pt Nanoparticles Supported on Hydrophobic Graphitized Carbon Nanofibers for Electrocatalysts Using Noncovalent Functionalization (pages 3954–3960)

      Hyung-Suk Oh and Hansung Kim

      Version of Record online: 24 AUG 2011 | DOI: 10.1002/adfm.201101177

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      1-Pyrenecarboxylic acid (PCA) is used to functionalize carbon nanofibers. Functionalization with PCA improves the distribution and loading of Pt, as well as reducing the sintering of Pt particles. Based on the carbon corrosion test, unlike oxidative acid treatment, the PCA treatment sustains the corrosion resistance of the CNFs because PCA functionalization treatment preserves the intrinsic properties of CNFs.

    5. Electrochemical Investigations of Polyethylene Glycol-Based “Soggy Sand” Electrolytes – From the Local Mechanism to the Overall Conduction (pages 3961–3966)

      Anna Jarosik, Christian Pfaffenhuber, Armin Bunde and Joachim Maier

      Version of Record online: 24 AUG 2011 | DOI: 10.1002/adfm.201100351

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      Local and long-range transport mechanism in soggy-sand electrolytes are elaborated using lithium salt containing polyetheleneglycol (blue)-silica (yellow) composites as an example. The local mechanism implies higher conductivity of the cation and lower conductivity of the anion. The overall conductivity requires a percolating silica network.

    6. Crystallization and Microstructure of Yttria-Stabilized-Zirconia Thin Films Deposited by Spray Pyrolysis (pages 3967–3975)

      Barbara Scherrer, Sebastian Heiroth, Regina Hafner, Julia Martynczuk, Anja Bieberle-Hütter, Jennifer L. M. Rupp and Ludwig J. Gauckler

      Version of Record online: 30 AUG 2011 | DOI: 10.1002/adfm.201101268

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      This paper presents the microstructural characteristics of YSZ thin films deposited by spray pyrolysis. After deposition, YSZ thin films are amorphous with some 3 nm sized crystallites having a microstrain of 4%. During heating, the YSZ starts to crystallize; at 600 °C about 40% of the crystallization enthalpy is released and the crystallites have grown to a size of 5 nm with 1% microstrain. The material is fully crystalline at 900 °C or, after 17 h, at 600 °C.

    7. Direct Observation of Ag Filamentary Paths in Organic Resistive Memory Devices (pages 3976–3981)

      Byungjin Cho, Jin-Mun Yun, Sunghoon Song, Yongsung Ji, Dong-Yu Kim and Takhee Lee

      Version of Record online: 24 AUG 2011 | DOI: 10.1002/adfm.201101210

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      The bipolar switching effect of Ag/WPF-BT-FEO/heavily-doped p-type poly Si organic memory devices is shown to be due to the formation and rupture of Ag conductive filamentary paths using transmission electron microscopy and energy-dispersive X-ray spectroscopy. Conducting atomic force microscopy measurements were also used to visualize the localized conductive paths. With a clear understanding of the switching mechanism, this study may contribute to the optimization of device scaling or improvements in memory performance.

    8. Fracture of Sub-20nm Ultrathin Gold Nanowires (pages 3982–3989)

      Yang Lu, Jun Song, Jian Yu Huang and Jun Lou

      Version of Record online: 24 AUG 2011 | DOI: 10.1002/adfm.201101224

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      Single crystalline ultrathin gold nanowires may fracture in two modes under tensile loading, displaying distinctively different fracture morphologies and ductility. In the samples that experienced brittle-like fracture, (111) twin structures were found to form during initial loading stage due to small misalignment and the final failure usually occurs along or near one of the twin regions.

    9. Br-Doped Li4Ti5O12 and Composite TiO2 Anodes for Li-ion Batteries: Synchrotron X-Ray and in situ Neutron Diffraction Studies (pages 3990–3997)

      Guodong Du, Neeraj Sharma, Vanessa K. Peterson, Justin A. Kimpton, Dianzeng Jia and Zaiping Guo

      Version of Record online: 1 SEP 2011 | DOI: 10.1002/adfm.201100846

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      Li4Ti5O12-xBrxanodes that contain secondary phases such as TiO2 can show higher discharge capacities. A selected region of in situ ND data of a Li4Ti5O12/TiO2 composite electrode highlights the time-dependent Li extraction process in LixTiO2 observed by the increase in 2θ value of the (112) reflection indicated by the arrow.

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